BILLINGS — Montana on Thursday joined North Dakota and South Dakota as states that are moving to curtail the hunting of sage grouse in response to a continued decline in the game bird’s population.

State wildlife commissioners gave tentative approval to a proposal to cancel or scale back Montana’s two-month hunting season, which is slated to open in September.

After hunting advocates lined up against the initial proposal for an outright closure, Fish and Wildlife Commission Chairman Dan Vermillion said less drastic measures were still on the table. Those include shortening the season, limiting how many birds a hunter can shoot and allowing hunting to continue in some areas where the decline has not been as severe.

“I’m not convinced that hunting-based mortality really addresses the bigger issue, which is habitat,” Vermillion said.

A final vote is expected in July.

North Dakota has not allowed sage-grouse hunting for the past several years. South Dakota cancelled its season last year and is not expected to have a hunt in 2014.

Found in 11 states and two provinces, sage grouse have suffered a steep decline in recent decades. Last year’s count of males on sage-grouse breeding grounds in Montana was the lowest recorded since 1980.

The birds are known for an elaborate mating ritual in which the males strut around breeding grounds known as leks and puff out their breasts in a colorful display meant to attract females and drive away other males.

The U.S. Fish and Wildlife Service faces a 2015 deadline to decide if the chicken-sized, ground-dwelling bird needs sweeping federal protections. States across the West have scrambled to come up with conservation measures that could head off a threatened or endangered listing.

Agriculture, energy development and disease are greater threats than hunting, biologists said.

Ben Deeble with the Big Sky Upland Bird Association said politics, not biology, appeared to drive the proposal to shut down the season.

“Hunters make a major contribution to sage grouse conservation,” Deeble said. “If we lose 100 percent of our hunting opportunity, it’s unfair. We certainly don’t expect all of the energy industry to be shut down by sage grouse or all the agriculture industry to be shut down.”